Top feed means for sewing machines

ABSTRACT

Top feed means for sewing machines having a presser foot and a spring biased top feed foot linked to a feeding and raising drive and connected with a carrier on the presser bar, which top feed foot is connected to a link connected with the feeding mechanism and joined with the carrier by a lever connected with the raising elements, which is pivotally supported by the carrier and reaches below a roller element that is arranged on the top feed foot.

United States Patent Herbert Wenz;

Heinrich Berg, Kaiserslautern, Palatinate, Germany July 2, 1969 Mar. 16, 197 1 GM. Pfaff AG Kaiserslautern, Palatinate, Germany InventorsAppl. No. Filed Patented Assignee TOP FEED MEANS FOR SEWING MACHINES 4Claims, 2 Drawing Figs.

U.S. Cl 112/212 Int. Cl D05b 27/04 Field of Search 112/212, 207

[56] References Cited UNITED STATES PATENTS 488,964 12/1892 Dolloff112/207 1,129,854 3/1915 Dahl l12/212X 3,009,432 11/1961 Reeber et al112/212 Primary Examiner-Richard J. Scanlan, Jr. Attorney Robert H.Jacob l 42- x24 17 2 0 j 0 1 O 1 O i a;

Patented March 16, 1971 INVENTOR.

1951985197 VIII 11w BY Y P/OVBIWG- TOP FEED MEANS FOR SEWING MAQIIINIESBACKGROUND OF THE INVENTION The invention relates to the feed means forsewing machines. More in particular, the invention is concerned with atop feed means or device for sewing machines having a presser foot and atop feeding foot, each of which is connected by connecting links with aforward feeding and a raising drive means and with a support or carrierconnected to the presser bar.

In known devices of this type undesirable oscillation phenomena arise asa result of high operating velocities which are caused by the returnimpact of the top feed foot upon the material beingsewn, or upon thelower material feed dog, and by the mass forces of the movable parts.The top feed or presser foot then is raised up from the material fromtime to time during its forward feeding phase. As a result, the materialcan then no longer be evenly fed or transported.

In order to reduce the inertia forces or momentum, an arrangement hasbecomeknown where the connection between the presser bar and the topfeed foot is made by a feed joint. This joint arrangement, however, isvery costly if faultless guiding is to be insured.

Furthermore, in the known arrangement a spring is provided in a sleevebetween the presser bar and the needle bar. As a result of the smallspace between the feeding joint and the head of the machine, the springmay only be of small structural height. In that case however, only asmall path is available for the spring so that it is necessary to selecta spring having a relatively steep characteristic. This, in turn,results in that with sewing material of different thickness the pressureat any time upon the top feed foot is of different magnitude. Thus, itis necessary to readjust the spring tension as the thickness of thematerial changes.

SUMMARY OF THE INVENTION In order to eliminate these shortcomings, it isan object of the invention to provide a top feedmeans wherethe massbeing moved is still further reduced as compared to known arrangements.

In accordance with the invention, this problem is solved in that the topfeed foot is connected to a link that is connected with the forward feedgear and linked to the support or carrier, while furthermore a leverconnected with the raising gear, rockably supported on the carrierreaches below a rolling body provided on the top feed foot.

1 In order to avoid a complicated guide means for the top feed foot anarrangement can be employed where the spring presses a ball that islimited in its lateral movement by an abutment surface upon a pressuresurface provided upon the top feed foot.

In accordance with a further object of the invention the spring can bearranged within the presser foot bar. In this manner there results aspacially advantageous accommodation of the spring, and simultaneouslythe use of a spring having a relatively long path of movement is madepossible.

BRIEF DESCRIPTION OF THE DRAWING An embodiment of the invention isillustrated in the accompanying drawing, in which:

FIG. I is a front perspective view of a sewing machine provided with thetop feeding means in accordance with the invention; and

IFIG. 2 is an enlarged illustration of the top feeding means, partly insection.

DESCRIPTION OF THE INVENTION In the housing I of the sewing machine apresser foot bar 2 provided with a bore 3 is journaled at the lower endof which a carrier 4 is threadedly secured. The carrier 4 is providedwith a rearwardly extending arm 5, and in addition it supports thepresser foot 6.

In the housing I of the machine there is furthermore journaled an armshaft 7, which drives the needle bar 3 with the needle 9 in a knownmanner by way of driving elements (not illustrated). Besides, aneccentric III as well as an eccentric II are mounted upon the arm shaft7.

The eccentric III is encompassed by the eccentric bar I2 upon which isjournaled a sliding block 14 guided in the ad justable sliding trackmember 13. The direction of the guiding path of the adjustable track 13is adjusted by means of a setting shaft 15 journaled in the housing,with a manual lever I6 (FIG. l) the connection of which with the settingshaft is not illustrated. The setting lever 16 extends from the housingI. By means of the setting shaft the magnitude and direction of thefeeding movement of the lower feed dog 18 extending through the stitchplate 17 is determined.

Due to the controlled guidance of the sliding block 14 in the settingtrack 13 the end of the eccentric bar 12 supporting the sliding block I4has imparted to it a lateral movement depending on the inclination ofthe setting and guiding track 13. This lateral movement of the eccentricbarv I2 is transmitted by a link bar 19 by way of a double lever 20 anda link 21 journaled to the stud 22 of a joint, which is carried by apair of links 23 connected to the arm 5.

The eccentric l1 drives an eccentric bar 24 which by means of abellcrank lever 25 and a link 26, rocks a lever 28 journaled on anextension 27 of the arm 5 of the carrier 4.

The free arm 30 of the lever 28 provided with a smooth surface 29extends below a roller member 32 rotatably journaled upon a stud 3I. Thestud 31 is secured in the split shank 33 of a top feed foot 35 journaledupon the joint stud 22 by way of an arm 34.

The wall 36 of the shank 33 extending below the support 4 has a pressuresurface 37 for a ball 38 which is movable within a conically shapedexpansion of a bore 40 in the support 4 that is limited by an abutmentsurface 39.

The bore 40 constitutes an extensions of the bore 3 provided in thepresser bar 2. In the bore 3 a spring 41 is received, one end of whichrests against a setting screw 42 threadedly received in the upper end ofthe presser bar 2 and the other end of which rests against a guidingbolt 43 that is guided in the bores 3 and 40 and biased against the ball38.

A flat spring or leaf spring 44 secured in the housing I in a knownmanner presses with its end against a ball 46 disposed in a recess 45 ofthe setting screw 42. This ball passes on this pressure by way of thepresser foot bar 2 to the presser foot 6. This presser foot presses thesewing material against the lower presser material feed dog I8 oragainst the stitch plate 17.

By turning the setscrew 42 in or out, the pressure of the presser foot 6upon the material can be changed.

A raising or lifting member 47 is secured to the presser foot bar 2which has an abutment surface 48 with an abutment 49 for the manuallever 50 rockably secured in the housing I.

The arrangement operates as follows: As the arm shaft 7 rotates, the twoeccentrics I0 and II are driven together with the other sewing tools ofthe machine. The eccentric l1 rocks the bellcrank lever 25 by way of theeccentric bar 24, and the bellcrank lever rocks the lever 28 by way ofthe link 26. In this manner the arm 30 of lever 28 is raised andlowered.

As the arm 30 is raised, its upper surface 29 also presses the top feedfoot 35 upwardly by way of the roller member 32. The raising in thisconnection takes place against the pressure brought to bear by spring 41upon the ball 38. When the top feed foot 35 is raised, the materialbeing sewn is pressed only by the pressure of the presser foot 6 whichis under the pressure of flat spring 44.

By lowering the arm 30, its surface 29 becomes separated from the rollerelement 32, as soon as the top feed foot 35 is seated on the materialbeing sewn or on the bottom feed dog I8 under the pressure of spring 41.The presser foot 6 which is under the bias of leaf spring 44 and the topfeed foot 35 under the effect of spring 41 now press down together onthe material.

Due to the rocking of the eccentric bar 12 caused by the eccentric orcam the sliding block 14 is displaced in the track 13. Depending on theposition of this track 13, which can be changed by the manual levershown in FIG. 1, the double lever is more or less strongly deflected.The top feed foot 35 connected with it by way of link 21 effectscorrespondingly large feeding movements.

These horizontal movements of the top feed foot 35 are made possible bythe roller bearing guidance existing between roller element 32 and thesurface 29 as well as also between surface 37 and ball 38 as wellbetween it and the bolt 43. The abutment surface 39 in this connectionlimits the movement of ball 38 and thereby its relative position withrespect to surface 37 and wall 36.

In order to raise the presser foot 6 the manual lever 50 is swungupwardly. The abutment 49 thereby raises the lifting member 47 and thepresser bar 2 together with the presser foot 6. Due to the linking ofthe top feed foot 35 by the pair of links 23, as well as also thelinking of the lever 28 to the support 4 that is rigidly connected withthe presser bar 2 the top feed foot 35 is thus raised to the sameextent.

Having now described out invention with reference to the embodimentillustrated in the drawing, what we desire to protect by letters patentis set forth in the appended claims.

We claim:

1. Top feed means for sewing machine of the type having a housing, adrive shaft in said housing, a presser foot bar movable axially in saidhousing and supporting a presser foot a first spring disposed in saidhousing biasing said presser foot bar, a carrier secured to said presserfoot bar, a top feed foot and a link connecting said top feed foot withsaid carrier, a second spring for biasing said top feed foot downwardly,means operably connecting said top feed foot with said drive shaft forimparting feed movements thereto, a lever pivotally connected to saidcarrier, and means connecting said lever to said drive shaft forimparting rocking movements to said lever, and a roller rotatablysupported on said top feed foot, said lever extending below said rollerfor engaging said roller while executing rocking movements.

2. Top feed means in accordance with claim 1, wherein said secondbiasing spring and a guiding bolt are in said presser foot bar, anabutment on said top feed foot and a ball intermediate said abutment andsaid guiding bolt, and said carrier defining a conical surface aroundsaid ball.

3. Top feed means in accordance with claim 1 including means operativeto apply the pressure of said second spring to said top feed foot, saidmeans comprising a pressure surface on said top feed foot, a ball inengagement with said pressure surface, and an abutment surface proximatesaid carrier limiting lateral movement of said ball.

4. Top feed means in accordance with claim 3, where said second springis arranged inside said presser bar.

1. Top feed means for sewing machine of the type having a housing, adrive shaft in said housing, a presser foot bar movable axially in saidhousing and supporting a presser foot a first spring disposed in saidhousing biasing said presser foot bar, a carrier secured to said presserfoot bar, a top feed foot and a link connecting said top feed foot withsaid carrier, a second spring for biasing said top feed foot downwardly,means operably connecting said top feed foot with said drive shaft forimparting feed movements thereto, a lever pivotally connected to saidcarrier, and means connecting said lever to said drive shaft forimparting rocking movements to said lever, and a roller rotatablysupported on said top feed foot, said lever extending below said rollerfor engaging said roller while executing rocking movements.
 2. Top feedmeans in accordance with claim 1, wherein said second biasing spring anda guiding bolt are in said presser foot bar, an abutment on said topfeed foot and a ball intermediate said abutment and said guiding bolt,and said carrier defining a conical surface around said ball.
 3. Topfeed means in accordance with claim 1 including means operative to applythe pressure of said second spring to said top feed foot, said meanscomprising a pressure surface on said top feed foot, a ball inengagement with said pressure surface, and an abutment surface proximatesaid carrier limiting lateral movement of said ball.
 4. Top feed meansin accordance with claim 3, where said second spring is arranged insidesaid presser bar.